Transducer with mesa

Abstract

An ultrasonic transducer having a container, a base an actuator and a membrane system. The membrane system can include a membrane, a mesa and a standoff. The mesa can be shaped to achieve one or more target frequencies and other target vibrational properties, such as amplitudes. The actuator may be a flexure having one or more electroactive materials, such as piezoelectric and/or electrostrictive materials. The flexure may be fixed at one end to a wall of the container be in communication with the membrane system at or around its other end. The actuator may be in contact with the membrane system through the mesa and/or the standoff. The standoff may include an adhesive filled with beads to achieve a specific thickness.

The invention claimed is: 
     
       1. An apparatus comprising:
 a membrane system comprising:
 a membrane; and 
 a mesa attached to the membrane and configured to modulate vibration of the membrane, the mesa comprising a material having a patterned shape; and 
 
 an actuator mechanically linked to the membrane system at a first end of the actuator and to a wall element of a container at a second end of the actuator, the first end of the actuator comprising a distal end. 
 
     
     
       2. The apparatus of  claim 1 , wherein the actuator comprises piezoelectric material. 
     
     
       3. The apparatus of  claim 1 , wherein the actuator comprises an electrostrictive material. 
     
     
       4. The apparatus of  claim 1 , wherein the actuator is mechanically linked to the membrane through the mesa. 
     
     
       5. The apparatus of  claim 1 , further comprising a standoff disposed between the actuator and the mesa or membrane. 
     
     
       6. The apparatus of  claim 5 , wherein the standoff comprises an adhesive filled with beads. 
     
     
       7. The apparatus of  claim 5 , wherein the standoff comprises a material having a shape of at least one from the group of: a disc, an ellipse, a regular polyhedron, an irregular polyhedron, a curved portion and an irregular portion. 
     
     
       8. The apparatus of  claim 1 , wherein the membrane comprises a first material type and wherein the material having a patterned shape of the mesa comprises a second material type. 
     
     
       9. The apparatus of  claim 8 , wherein the first material type is aluminum and the second material type is copper. 
     
     
       10. The apparatus of  claim 8 , wherein the first material type is polyimide film and wherein the second material type is copper. 
     
     
       11. The apparatus of  claim 8 , wherein the first material type and the second material type are the same material type. 
     
     
       12. The apparatus of  claim 8 , wherein the first material type is a polymer and wherein the second material type is a metal. 
     
     
       13. The apparatus of  claim 1 , wherein the membrane or the mesa is comprised of at least one material selected from the group of aluminum, a polymer, copper, stainless steel, brass, diamond, sapphire, titanium, a covalently bonded ceramic or crystal, or a metal alloy. 
     
     
       14. The apparatus of  claim 1 , wherein the patterned shape of the mesa includes an H shape. 
     
     
       15. The apparatus of  claim 1 , wherein the patterned shape of the mesa includes an annulus. 
     
     
       16. The apparatus of  claim 1 , wherein the patterned shape of the mesa includes a circular shape. 
     
     
       17. The apparatus of  claim 1 , wherein the patterned shape of the mesa includes a cross. 
     
     
       18. The apparatus of  claim 1 , wherein the patterned shape of the mesa includes a torus. 
     
     
       19. The apparatus of  claim 1 , wherein the patterned shape of the mesa includes a torus and a cross. 
     
     
       20. The apparatus of  claim 1 , wherein the patterned shape is selected to achieve a target frequency. 
     
     
       21. The apparatus of  claim 1 , wherein the patterned shape is selected based on at least one target property of ultrasound that is generated by the apparatus. 
     
     
       22. The apparatus of  claim 21 , wherein the at least one property is selected from the group consisting of: power, phase, frequency and beam pattern. 
     
     
       23. The apparatus of  claim 1 , wherein the mesa has varying thicknesses. 
     
     
       24. The apparatus of  claim 1 , wherein the membrane system has an effective stiffness ranging from 0.1 kN/m to 30.0 MN/m. 
     
     
       25. The apparatus of  claim 1 , wherein the membrane system has an effective stiffness ranging from 100 kN/m to 1 MN/m. 
     
     
       26. The apparatus of  claim 1 , wherein the membrane system has an effective mass of from 100 micrograms to 130 milligrams. 
     
     
       27. The apparatus of  claim 1 , wherein the membrane system has an effective mass of from 0.1 mg to 5 mg. 
     
     
       28. The apparatus of  claim 1 , wherein the membrane system has an effective mass of from 0.75 mg to 5 mg. 
     
     
       29. The apparatus of  claim 5 , wherein the standoff is comprised of an epoxy filled with beads. 
     
     
       30. The apparatus of  claim 1 , wherein a portion of the piezoelectric actuator is in mechanical contact with a portion of the mesa or membrane substantially at the center of the membrane. 
     
     
       31. The apparatus of  claim 1 , wherein a portion of the piezoelectric actuator is in mechanical contact with a portion of the mesa or membrane at an off-center location of the membrane. 
     
     
       32. The apparatus of  claim 1 , wherein the mesa has a non-uniform stiffness. 
     
     
       33. The apparatus of  claim 5 , wherein the standoff comprises a material having a shape including at least one from the group of: a disc, an ellipse, a regular polyhedron, an irregular polyhedron, a torus, a curved portion and an irregular portion.